qtty-ffi

C-compatible ABI bridge for qtty.

qtty-ffi exposes stable carrier structs, unit identifiers, status codes, and conversion/formatting functions so C and C++ consumers can use qtty's unit registry without reimplementing conversion logic.

Highlights

• QttyQuantity and QttyDerivedQuantity POD carriers
• stable UnitId and DimensionId discriminants
• extern "C" entry points for construction, conversion, inspection, and formatting
• generated header at include/qtty_ffi.h
• optional Rust-side qtty_serde and pyo3 helpers

Install

[dependencies]
qtty-ffi = "0.8.0"

C example

#include "qtty_ffi.h"

qtty_quantity_t meters;
qtty_quantity_make(1000.0, UNIT_ID_METER, &meters);

qtty_quantity_t kilometers;
if (qtty_quantity_convert(meters, UNIT_ID_KILOMETER, &kilometers) == QTTY_OK) {
    /* kilometers.value == 1.0 */
}

Rust example

use qtty::Meter;
use qtty_ffi::{QttyQuantity, UnitId};

let qty: QttyQuantity = Meter::new(12.5).into();
assert_eq!(qty.unit, UnitId::Meter as u32);

Related crates

• qtty: user-facing Rust facade
• qtty-core: low-level unit type system
• qtty-derive: proc-macro for custom unit markers